All this time the doctrines of Luther had been making progress and spreading among all classes in Prussia and Germany.  In 1522 the grand master went to Nuremberg to consult with the Lutherans there, and shortly afterward he visited Luther himself at Wittenberg.  Luther’s advice was decided and trenchant.  He poured contempt upon the rules of the order, and advised Albert to break away from it and marry.  Melancthon supported Luther’s counsels.  Shortly after, Luther wrote a vigorous letter to the knights of the order, in which he maintained that it was of no use to God or man.  He urged all the members to break their vow of celibacy and to marry, saying that it was impossible for human nature to be chaste in any other way, and that God’s law, which commanded man to increase and multiply, was older than the decrees of councils and the vows of religious orders.  At the request of the grand master he also sent missionaries into Prussia to preach the reformed doctrines.  One or two bishops and many of the clergy accepted them, and they spread rapidly among the people.  Services began to be said in the vulgar tongue, and images and other ornaments were pulled down in the churches, especially in the country districts.

In 1525 Albert met the King of Poland at Cracow, and formally resigned his office as grand master of the Teutonic order, making over his dominions to the King, and receiving from him in return the title of hereditary Duke of Prussia.  Shortly afterward he followed Luther’s advice, and married the princess Dorothea of Denmark.  Many of the knights followed his example.  The annals and archives of the order were transferred to the custody of the King of Poland, and were lost or destroyed during the troubles that subsequently came upon that kingdom.

A considerable number of the knights refused to change their religion and abandon their order, and in 1527 assembled in chapter at Mergentheim to consult as to their plans for the future.  They elected Walter de Cronberg grand master, whose appointment was ratified by the Emperor, Charles V. In the religious wars that followed, the knights fought on the side of the Emperor, against the Protestants.  In 1595 the commandery of Venice was sold to the Patriarch and was converted into a diocesan seminary; and in 1637 the commandery of Utrecht was lost to the order.  In 1631 Mergentheim was taken by the Swedes under General Horn.

In the war against the Turks during this period some of the knights, true to the ancient principles of their order, took part on the Christian side, both in Hungary and in the Mediterranean.  In the wars of Louis XIV, the order lost many of its remaining commanderies, and by an edict of the King, in 1672, the separate existence of the order was abolished in his dominions, and its possessions were conferred on the Order of St. Lazarus.

When Prussia was erected into a kingdom, in 1701, the order issued a solemn protest against the act, asserting its ancient rights over that country.  The order maintained its existence in an enfeebled condition till 1809, when it was formally abolished by Napoleon.  In 1840 Austria instituted an honorary order called by the same name, and in 1852 Prussia revived it under the designation of the Order of St. John.